Polygonal hot-fill container, package and method of making

ABSTRACT

A plastic container includes a plastic body having a polygonal sidewall contour with rounded corners on a cylinder of revolution and flat panels extending between the corners chordally of the cylinder of revolution. In the preferred embodiments of the invention, a label is disposed on an exterior surface of at least one of the flat panels, and most preferably extends circumferentially around the exterior surface of the container sidewall. Upon filling the container with hot liquid and capping the container, the flat panels bow radially inwardly as the liquid cools. However, any labeling placed on the container, either before or after cooling, is secured to the panels as well as the rounded corners, and does not wrinkle or crinkle during storage or use.

The present invention is directed to hot-fill container packages, and more particularly to a container, a package and a method making the package, which are particularly well suited for hot-fill applications.

BACKGROUND AND SUMMARY OF THE INVENTION

In so-called hot-fill packages, a container is filled with hot liquid product and capped while the liquid product is still hot. As the liquid cools, the reduction in liquid volume creates a vacuum within the package (i.e., an internal pressure that is less than the surrounding atmospheric pressure). A label may be applied to an exterior surface of the container either before or after filling.

When the container is of relatively rigid construction, such as glass construction for example, the hot-fill process does not present a problem relative to distortion of the container because the container sidewall is strong enough to withstand the forces resulting from the pressure differential between the container exterior and interior. However, when the container is of less rigid construction, such as molded plastic for example, the container sidewall distorts inwardly as the liquid cools. It has been proposed to provide vacuum panels in the container sidewall to absorb the distortion as the liquid product cools, leaving the remainder of the sidewall relatively undistorted. However, the corner or post areas in containers of this type tend to be relatively weak, and can become dented during the production process. Furthermore, any label applied to the container undesirably “crinkles” in a user's hand because of the absence of contact and adhesion entirely around the container sidewall. It is therefore an object of the present invention to provide a container, a closure and container package and a method of making such a package, which are particularly adapted for use in hot-fill applications, which accommodate creation of the vacuum within the container as the product cools without substantially distorting the overall package envelope, and in which any labeling on the container remains secured to the container without wrinkling or crinkling during use.

The present invention embodies a number of different aspects, which can be implemented separately from or more preferably in combination with each other.

A plastic container in accordance with a first aspect of the invention includes a plastic container body having a polygonal sidewall contour with rounded corners on a cylinder of revolution and flat panels extending between the corners chordally of the cylinder of revolution. The polygonal sidewall contour preferably is selected from the group consisting of square and pentagonal. A label may be located on an exterior surface of at least one of the panels, and extends circumferentially around an exterior surface of the sidewall. When the container is filled with hot liquid and thereafter cools, the flat panels bow radially inwardly. However, any labeling on the flat panels, placed before or after filling, is in contact and adheres to a smooth continuous surface, and does not wrinkle or crinkle during use.

In accordance with a second aspect of the present invention, a plastic container includes a plastic body having a polygonal sidewall contour with rounded corners on a cylinder of revolution and flat panels extending between the corners chordally of the cylinder of revolution. In the preferred embodiments of the invention, a label is disposed on an exterior surface of at least one of the flat panels, and most preferably extends circumferentially around the exterior surface of the container sidewall, either before or after filling. Upon filling the container with hot liquid and capping the container, the flat panels bow radially inwardly as the liquid cools. However, any labeling placed on the container remains secured to the flat panels as well as the rounded corners, and does not wrinkle or crinkle during storage or use.

A filled closure and container package in accordance with a third aspect of the invention includes a plastic container having a body and a finish, a liquid product within the interior of the container body, and a closure applied to the finish. The body interior is under vacuum and sealed by the closure. The container body has a cross section that includes rounded corners and concave panels extending between the corners. A label is adhered to an exterior surface of at least one of the container sidewall panels, either before or after filling the container, and assumes the concave contour of the panel exterior surface. In the preferred embodiments of the invention, the label comprises a sheet label extending entirely around the exterior surface of the container body and being adhered to the corners and the concave panels.

A method of making a package in accordance with yet another aspect of the invention includes providing a container having a plastic body with a polygonal sidewall, rounded corners on a cylinder of revolution and flat panels extending between the corners chordally of the cylinder of revolution. The container is filled with hot liquid, capped and allowed to cool so that the flat panels distort radially inwardly due to creation of a vacuum as the liquid cools within the container. A label is adhesively applied to the container sidewall, either before filling the container with hot liquid or after filling and the contents cool, such that the label is adhered to an exterior surface of the corners and the panels.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with additional objects, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which:

FIG. 1 is a side elevational view of a labeled closure and container package in accordance with one exemplary but presently preferred embodiment of the invention;

FIG. 2 is an elevational view of the container in FIG. 1 prior to filling and capping;

FIG. 3 is a perspective view of the container illustrated in FIG. 2;

FIG. 4 is a sectional view taken substantially along the line 4-4 in FIG. 2;

FIG. 5 is a schematic diagram of the container cross section in FIG. 4 illustrating forces applied thereto during cooling of the package contents;

FIG. 6 is a schematic sectional view similar to that of FIG. 5 but showing distortion of the container sidewall during cooling;

FIG. 7 is a sectional view taken substantially along the line 7-7 in FIG. 1 showing the final cross sectional contour of the closure and container package after cooling;

FIG. 8 is a perspective view of an unlabeled and unfilled container in accordance with another aspect of the present invention;

FIG. 9 is a sectional view of the container sidewall in FIG. 8;

FIG. 10 is a view, similar to that of FIG. 6, of the container in FIGS. 8-9 after filling;

FIG. 11 is a sectional view, similar to that of FIG. 9, but illustrating another embodiment of the invention; and

FIG. 12 is a sectional view, similar to that of FIG. 10, but of the embodiment of FIG. 11.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 illustrates a closure and container package 20, in accordance with one exemplary embodiment of the invention, as including a container 22 and a closure 24. Container 22 is of molded plastic construction, such as blow-molded PET construction, and includes a shoulder portion 25, a bottom or heel portion 26 and a sidewall 28 extending entirely around the container between the shoulder and bottom portions. Shoulder and bottom portions 25, 26 may be of any suitable construction, preferably having a circular contour as viewed from the axial direction to operate as “bumpers” during handling of the container and package. Closure 24 may be of any suitable construction, such as molded plastic construction, for sealing the interior of container 22. A sheet label 30 extends around the exterior surface of container sidewall 28.

FIGS. 2-3 illustrate container 22, prior to filling and capping, in accordance with one exemplary embodiment of the invention. Shoulder and bottom portions 25, 26 and sidewall 28 form a container body 32 from which a finish 34 extends for securement of closure 24 (FIG. 1). The geometry of finish 34 illustrated in FIGS. 2 and 3 is strictly exemplary. As viewed in diametric cross section (FIG. 4) prior to filling, sidewall 28 is of polygonal contour, preferably either pentagonal as shown or square. The contour of sidewall 28 includes angularly spaced rounded posts or corners 34 and flat panels 36 that extend between corners 34. Rounded corners 34 lie on a cylinder of revolution 38 (FIG. 5), and flat panels 36 extend chordally across such cylinder of revolution. Container sidewall 28 preferably is of substantially uniform wall thickness entirely around the sidewall. There is a smooth transition from corners 34 to panels 36, which is to say that there are no ribs or channels that separate these portions of the sidewall.

In the embodiment of the invention illustrated in FIGS. 2-4, label 30 is exteriorly applied to container sidewall 28 prior to filling. Label 30 preferably is in the form of a rectangular sheet that extends entirely around sidewall 28, and may comprise a pressure-sensitive self-adhesive sheet label that is rolled onto the container. However, as will be described later, label 30 may be applied to the container after filling, either before or after cooling of the container contents. It is also within the scope of the present invention in its broadest aspects, although not presently preferred, to employ spot labels applied to one or more of the panels 36 only.

FIG. 5 illustrates force vectors acting on container sidewall 28 following filling and capping of the container and as the container contents cool. Stress forces F act entirely around the container sidewall due to the pressure differential between the container exterior (normally ambient pressure) and the container interior as the liquid product cools. At panels 36, these stress forces F are perpendicular to the plane of each panel. At the corners 34, however, the forces F are divided into geometric components, each of which is less than F. As a result, the centers of the panels collapse under vacuum, and the volume reduction from the panel collapse eliminates the vacuum within the container and preserves the geometries of the corners. Thus, sidewall panels 36 assume an outwardly concave contour 36 illustrated in FIG. 6, while the corners 34 move radially inwardly a slight amount from the original or first cylinder of revolution 38 to a final or second cylinder of revolution 40. Panels 36 have a uniform radius of curvature 41, all panels 36 and radii 41 preferably being identical. Label 30, being adhered to the exterior surface of the container sidewall, follows the inward movement of the container corner and panel areas, stretching as required to accommodate inward flexing of the container sidewall panels but without becoming separated from the container sidewall panels or corners. The amount of radially inward flexure is dependent upon a number of factors, including initial product temperature, sidewall strength, overall container geometry, etc. FIG. 7 illustrates the final contour of container sidewall 28 with attached label 30 and container contents 42.

As noted above, FIGS. 2-4 illustrate label 30 having been applied to empty container 22, such as by the container manufacturer. Label 30 may be a self-adhesive pressure-sensitive label that is rolled onto the sidewall of the container following the molding operation. As an alternative, the label may be applied by the packager after filling and capping of the container, but before the container contents have an opportunity substantially to cool, so that the container sidewall geometry remains substantially the same as the original geometry and has not yet had an opportunity to distort toward the geometry of FIGS. 6 and 7. When the label is applied by the product packager, a roll-on pressure-sensitive label or a heat-shrinkable label sleeve may be employed. It is also envisioned that individual spot labels may be applied to the flat panels of the container sidewall, although this would not be preferred because of additional expense. As another alternative, which is presently preferred, the label may be applied by the packager after filling, capping and washing, when the container is at or near room temperature and the panels have bowed inwardly. A heat-shrinkable sleeve label is preferred for this application. This alternative has the advantage that the label will not become damaged or dirty during shipping and handling of the empty container, or during filling, capping and washing of the container.

FIGS. 8-9 illustrate a container 22 a, which is similar to container 22 of FIGS. 1-7 but is unlabeled. In this embodiment, the label (not shown) is heat-shrunk onto the container after it is hot-filled, capped and washed, and after the filled container cools to room temperature (FIG. 10) and the panels have bowed inwardly.

FIGS. 11-12 illustrate a square container 50 having corners 52 on a circle of revolution 54 and flat panels(as molded) 56 that extend between the corners chordally of cylinder 54. After filling with hot product 42 (FIG. 12), corners 52 move to a smaller cylinder of revolution 58, and panels 56 bow radially inwardly. Panels 56 have a uniform radius of curvature 60, all panels 56 and radii 60 preferably being identical. A label (not shown) may be applied before filling (FIG. 11), or more preferably after filling, capping, washing and cooling (FIG. 12) when the panels have bowed inwardly.

Container sidewall panels 36, 56 have been described as “flat,” which is the preferred configuration of these panels as molded. That is, the panels 36, 56 as initially molded should be substantially flat or planar, without substantial concavity or convexity. If the panels 36, 56 have substantial outward convexity, radial inward bowing of the panels as the package cools would apply outward forces to the corners of the container, tending to expand rather than contract the container sidewall and possibly leading to buckling and formation of waves in the sidewall panel contours. Likewise, substantial concavity in the panels 36, 56 as molded would make it difficult to apply labels to the containers without trapping air beneath the labels, which would create the wrinkles and crinkle-feel in the labels which the present invention seeks to eliminate. It should also be noted that the inward bending of the sidewall panels 36, 56 under internal vacuum pressure may become permanent in whole or in part due to creep of the plastic material of the sidewall, which would have no effect upon the present invention.

There have thus been disclosed a container, a package and a method of making a package that fully satisfy all of the objects and aims previously set forth. The invention has been described in conjunction with presently preferred embodiments thereof, and a number of modifications and variations have been discussed. Other modifications and variations will readily suggest themselves to persons of ordinary skill in the art. The invention is intended to embrace all such modifications and variations as fall within the spirit and broad scope of the appended claims. 

1. A method of making a package that includes the steps of: (a) providing a container that includes a plastic body with a polygonal sidewall having rounded corners on a first cylinder of revolution and flat panels extending between said corners chordally of said cylinder of revolution, (b) filling said container with hot liquid, (c) capping said container, and (d) allowing the filled and capped container to cool so that said flat panels bow radially inwardly and said rounded corners move radially inwardly from said first cylinder of revolution to a smaller second cylinder of revolution due to creation of a vacuum as said liquid cools within said filled and capped container.
 2. The method set forth in claim 1 comprising the additional step of: (e) applying a sheet label to said container sidewall such that the label is adhered to an external surface of said corners and said panels.
 3. The method set forth in claim 2 wherein said step (e) is carried out prior to said step (b).
 4. The method set forth in claim 2 wherein said step (e) is carried out subsequent to said step (c) but prior to said step (d).
 5. The method set forth in claim 2 wherein said step (e) is carried out subsequent to said step (d).
 6. A filled closure and container package that includes: a plastic container having a body and a finish, liquid product within an interior of said body, a closure applied to said finish, said body interior being under vacuum and sealed by said closure, said body having a cross section that includes radially inwardly displaced rounded corners and concave panels extending between said corners, and a label adhered to an exterior surface of at least one of said panels, having the concave contour of said exterior surface.
 7. The package set forth in claim 6 wherein said label extends entirely around an exterior surface of said body and being adhered to said corners and said concave panels.
 8. The package set forth in claim 6 wherein said concave panels have a uniform radius of curvature.
 9. The package set forth in claim 8 wherein said body cross section is polygonal, being selected from the group consisting of square and pentagonal.
 10. A labeled container for hot liquid filling applications, which includes: a container body having a polygonal sidewall contour with rounded corners on a cylinder of revolution and flat panels extending between said corners chordally of said cylinder of revolution, and a label extending circumferentially around an exterior surface of said sidewall, said label being adhered to said exterior surface of said corners and said flat panels, such that, upon filling and capping of the container body with hot liquid, distortion of said rounded corners and flat panels during cooling of the liquid does not separate said panels from said sheet label creating air gaps between said label and said panels.
 11. A plastic container for hot-fill liquid applications, which includes a plastic container body having a polygonal sidewall contour with rounded corners on a first cylinder of revolution and flat panels extending chordally of said cylinder of revolution, upon filling said container with hot liquid and capping said container, said flat panels being adapted to bow radially inwardly and said rounded corners being adapted to move radially inwardly to a smaller, second cylinder of revolution as the liquid cools.
 12. The container set forth in claim 11 further comprising a label adhered to at least one of said flat panels.
 13. The container set forth in claim 12 wherein said label extends continuously circumferentially around an external surface of said container body, being adhered to said corners and said panels and remaining adhered to said corners and panels during bowing of said panels following liquid hot-fill.
 14. The container set forth in claim 11 wherein said polygonal sidewall contour is selected from the group consisting of pentagonal and square.
 15. A package made on accordance with the method set forth in claim
 1. 16. A package made in accordance with the method set forth in claim
 2. 